What would be really impressive would be to reproduce the Hewlett Packard historic (HP-200A) using FETs and solid state approach to the large variable cap. If my memory is correct, each section of a ganged cap (like the one shown in the photo) were about 365pF max.

Anyone remember the 60° oscillator? I remember it from college, each RC leg shifts the frequency 60°, 3X60° is 180°, and since the transistor oscillator shifts the freq another 180° you have positive feedback.

Yeah. Except I know it as the "phase-shift oscillator". The phase shift doesn't need to be the same at each stage, the oscillator will find the frequency where the combined phase shift totals 180 and go happily on its way.

I think, even with equal value components, the phase shift per stage is not equal because of the parallel paths being different on the different stages, and the loading of the gain component on the last stage. Some manipulation of the values at each stage can make it closer, but "60° oscillator" is probably still optimistic.

Yep, but when you teach theory you don't always get into the messy details, those come later. When I was learning this stuff they didn't have SPICE, and the computer we got to use in the electronics class was a PDP brought in a trailer (a big trailer).

Like I said, it's been 30 years. The circuit stuck, even if the name didn't.

What would be really impressive would be to reproduce the Hewlett Packard historic (HP-200A) using FETs and solid state approach to the large variable cap. If my memory is correct, each section of a ganged cap (like the one shown in the photo) were about 365pF max.